The primary objective of this study is to evaluate the safety and toxicity profile of LY300502 administered by four different doses and to measure the reduction in serum DHT levels from baseline in patients treated at these doses to define the maximum biological effect (MBE) dose. This is a non-randomized dose finding study of LY300502 in patients with metastatic prostate cancer who have failed or are not candidates for convention hormonal therapy. LY300502 will be administered three times daily for a period of 12 weeks. In order to define the dose at which DHT suppression is maximized with acceptable safety and pharmacokinetic profiles, patients will be entered in four cohorts of eight patients each.